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Paul

Model output discussion - the beast arrives

Paul

Please only post model discussion in here! 
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11 minutes ago, nick sussex said:

Yes definitely , it’s turning into the Da Vinci Code low! :D

Its a very unusual set up, normally breakdowns occur with the main jet heading towards the UK. So the models have to juggle the energy , how much goes ne versus se.

Theres no real drive behind the low the main jet is heading towards Africa .

 

That's what is so frustrating. The low has no backing from the jet yet it moves aside -15c air with the softest of nudges.

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5 minutes ago, Snowy L said:

That's what is so frustrating. The low has no backing from the jet yet it moves aside -15c air with the softest of nudges.

Still all to play for could be big changes by tomorrows 06z run!

Edited by Ayrshire weather

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I was having a think as to why the gfs was ahead of the game on this breakdown when it was a very unusual background pattern

Why did it see the Azores upper trough engaging the cold pool headed west first?

we know that gfs has a bias to take things northeast so was it simply doing this with the Azores upper trough ??  

Or perhaps it’s bias to be overly zonal west to east also applies in a negative zonal phase east to west so it took the neg NAO further west earlier ??

ec amplification bias would certainly work against it finding this solution - it was about a day behind 

 

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13 minutes ago, Snowy L said:

That's what is so frustrating. The low has no backing from the jet yet it moves aside -15c air with the softest of nudges.

The supply of deep cold even without the low couldn’t be sustained unless another PV lobe dropped south to the east.

Scandi highs are rarely sustained for very long and you need the retrogression signal, in this instance the block goes too far to the west .

However even with that I wouldn’t rule out the models edging the subsequent pattern further south and south east .

As MWB noted the ECM clusters are all over the place .

Edited by nick sussex

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Interesting that the very latest METO weather warning updated about 4 minutes ago has both extended the snow and wind from thursday through to friday and now saturday.

Furthermore they are talking about uncertainty and delays with the northwards movement of any less cold air so the southern boundary has been moved south. Further spells of snow could also be arriving from the south later!

A slowly, slowly edging down of mean upper temps around that time is evident in the 06z GEFS compared to the 0z suite.

06z                                                                          0z

image.thumb.png.3517affea5392a78dab4f330d3e75936.pngimage.thumb.png.ddeab6c7972acb174997cf14ccb543f2.png

Small differences like these can make a huge difference to what happens to us on the ground on our tiny Island.

Looks like 'blizzardgate' has more in the tank yet. :D

PS: Longer term cold clustering is also edging the mean down as well.

 

Edited by Purga

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5 hours ago, bluearmy said:

Would like to have seen a fax for T96/108 - to see what they do with the front

awaiting the spreads to see how keen the eps are to take the jet more east than ne at the end of the weekend 

Are these the ones Blue? 

image001.gif

image003.gif

image004.gif

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2 minutes ago, Purga said:

Interesting that the very latest METO weather warning updated about 4 minutes ago has both extended the snow and wind from thursday through to friday and now saturday.

Furthermore they are talking about uncertainty and delays with the northwards movement of any less cold air so the southern boundary has been moved south. Further spells of snow could also be arriving from the south later!

A slowly, slowly edging down of mean upper temps around that time is evident in the 06z GEFS compared to the 0z suite.

06z                                                                          0z

image.thumb.png.3517affea5392a78dab4f330d3e75936.pngimage.thumb.png.ddeab6c7972acb174997cf14ccb543f2.png

Small differences like these can make a huge difference to what happens to us on the ground on our tiny Island.

Looks like 'blizzardgate' has more in the tank yet. :D

 

Indeed. They think further bands of snow could follow on Sat. Perhaps MOGREPS and UKV are showing this?

 

1C28E110-DE00-4CEB-89DF-CBC75E5923A7.jpeg

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I’m not sure where the correct place is to make this post. I think it is model related.

just wanted to know when an easterly is modelled, why is it so difficult to get showers to move across the country whereas in mainland Europe, the showers are more frequent over land with the cold air not moving over any sea. For example, Rome and Monaco gets snowfall as well as most parts of Germany. Whereas in the U.K., it is a struggle to get showers to the west despite the North Sea.

would somebody be able to enlighten me?

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2 minutes ago, Tim Bland said:

Indeed. They think further bands of snow could follow on Sat. Perhaps MOGREPS and UKV are showing this?

 

1C28E110-DE00-4CEB-89DF-CBC75E5923A7.jpeg

Yep, that's exactly what I was refering to Tim - just heard the 'ping' on my iphone a few minutes ago - hence the post.:)

Edited by Purga

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28 minutes ago, bluekipper said:

Are these the ones Blue? 

image001.gif

image003.gif

image004.gif

There are no faxes issued post T84 derived from the 00z runs 

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35 minutes ago, Tim Bland said:

Indeed. They think further bands of snow could follow on Sat. Perhaps MOGREPS and UKV are showing this?

 

1C28E110-DE00-4CEB-89DF-CBC75E5923A7.jpeg

Amber now here. I said yesterday that MOGS must have been been sniffing something. 

52E619C7-089B-48B1-8173-429FB231CA15.png

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6 minutes ago, bluearmy said:

There are no faxes issued post T84 derived from the 00z runs 

Soz,

Just asked our 'in house' forecaster as to what she thought of the GFS and its output..

This is her response:

'It’s tricky regarding the uncertainty, there are some signs that the GM is perhaps the outlier to the majority of other solutions at the minute for later in the week, hence some of the uncertainty! The GM wants to fragment the ppn moving NE across SE England through Friday and it’s this which is slightly at odds with other output so at the minute the chief has been making modifications to GM output, but like I said still a few days out.'

 

Anyway, back to the regionals...

 

 

 

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I am fairly new to this, so go easy.

This morning on the 0z and now the 6z IKON, I ran the animation I noticed how the Iberian Low interacts with the cold pool to our west and I wanted to run it past the more experienced members as it could be a reason why the models are struggling so much with the next few days. Its difficult to show in still pictures, but as the denser cold air interacts with the low, the low disrupts and fills, but at the same time the cold pool starts to rotate with the low around it, gradually getting faster. This initially pulls less cold air from the south, but as the cold pool starts to rotate starts pulling more cold in from the east.

I wish I could show this in animation as a .gif (maybe someone could give it a go) however, this can be seen at: https://www.meteociel.fr/modeles/icone_cartes.php?&ech=54&mode=0&map=0&archive=0

 

 

 

icon-0-3.png

icon-0-36.png

icon-0-54.png

icon-0-72.png

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18 minutes ago, Stevie B said:

I am fairly new to this, so go easy.

This morning on the 0z and now the 6z IKON, I ran the animation I noticed how the Iberian Low interacts with the cold pool to our west and I wanted to run it past the more experienced members as it could be a reason why the models are struggling so much with the next few days. Its difficult to show in still pictures, but as the denser cold air interacts with the low, the low disrupts and fills, but at the same time the cold pool starts to rotate with the low around it, gradually getting faster. This initially pulls less cold air from the south, but as the cold pool starts to rotate starts pulling more cold in from the east.

the cold pool meeting the azores upper trough is a big part of the problem. add to that there is no jet to steer the low initially and you have the dogs dinner we are dealing with !

the trend over the last couple runs is to shear the front apart as the initial low heads wnw and the upper trough disrupts somewhat. beginning to think that away from the sw quarter of the uk, there may not be too much snowfall as the less cold air heads north which seems quite clear on its initial approach timewise but then how much further does it get and what timescale ??

current modelling then brings the next low ne which meets less resistance with the jet now pushing it. this is where the spreads allow for differing broader solutions

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1 hour ago, high ground birmingham said:

I’m not sure where the correct place is to make this post. I think it is model related.

just wanted to know when an easterly is modelled, why is it so difficult to get showers to move across the country whereas in mainland Europe, the showers are more frequent over land with the cold air not moving over any sea. For example, Rome and Monaco gets snowfall as well as most parts of Germany. Whereas in the U.K., it is a struggle to get showers to the west despite the North Sea.

would somebody be able to enlighten me?

Good Q's and i also wonder why showers don't make it inland as far as i'd expect/hope.  The answers to your Q's will vary depending on what part of europe we look at but i'll have a pop at answering as an amateur but hopefully someone like John Holmes will give some expert answers.

If you look at the radar, it's actually currently very dry in France/Germany relative to  whats over the UK, the showers in northern Germany/Benelux may have resulted from an air mass that has travelled over the Baltic Sea plus i think the fax charts are showing a trough in the air flow for this location.  Italy/med coast is near some low pressure features and is arguably a battle ground scenario! The med sea temps will be higher than the N-Sea so if cold air engages with that then more precipitation. You will also need to consider the impact of mountain ranges like the Alps/Pyrenees/Transval Alps have on disrupting air flows.

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1 hour ago, Tim Bland said:

Indeed. They think further bands of snow could follow on Sat. Perhaps MOGREPS and UKV are showing this?

 

1C28E110-DE00-4CEB-89DF-CBC75E5923A7.jpeg

The UKV barely has any precip going east of the Isle of Wight, it's bizarre. That was on the 3z run anyway. The UKV runs every 3 hours, the 3z and the 15z go out to +120 hours while the rest go to +54. It is just about coming into view of the shorter range runs so perhaps we'll get a better picture. The 15z comes in at about 7pm or so.

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4 minutes ago, Nick L said:

The UKV barely has any precip going east of the Isle of Wight, it's bizarre. That was on the 3z run anyway. The UKV runs every 3 hours, the 3z and the 15z go out to +120 hours while the rest go to +54. It is just about coming into view of the shorter range runs so perhaps we'll get a better picture. The 15z comes in at about 7pm or so.

MMM  very westerly Based then.  must admit had to check were exactly the Ise of Wight was.     Can you give us a heads up when 7 oclock run comes out?.

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6 minutes ago, weirpig said:

MMM  very westerly Based then.  must admit had to check were exactly the Ise of Wight was.     Can you give us a heads up when 7 oclock run comes out?.

I will be out getting merry for my birthday but I will try and get a sneaky peek :D But it's *just* coming into view on the 12z and it does look a bit further east on what I can see. 

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22 minutes ago, weirpig said:

MMM  very westerly Based then.  must admit had to check were exactly the Ise of Wight was.     Can you give us a heads up when 7 oclock run comes out?.

Well Alderney seems to be having a wonderful snowy event, been non stop there by all accounts,  even have THE snow plough out on their airport, so there is snow south of the U.K. even the Isle of Wight. 

Edited by Tog

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So following saturdays tracker thought I'd now move onto Sunday since it looks like the colder air will still persist during the early half of the weekend.

Next is midday Sunday and I've decided to categorise this one by stating where the cold air boundary is on each ensemble member. I've used a surface temperature 4C as a general guide so if one is classed as the south coast, this means maximum temperatures on Sunday are below 4C everywhere from the south coast to Scotland. Anyway here are the results of the last 4 runs.

image.thumb.png.179b52a01e73f9affb47c97347060ade.png

For coldies we want the blue or the orange lines to rise to the top. It'd be nice for it to remain cold at the surface down here on the coast though that may be more difficult. Anyway the trend on recent runs is to stop milder air reaching all the way to Sctoalnd. Though where the colder temperatures extend to is highly uncertain. A small number of ensemble members still have surface temperatures struggling to get above freezing by Sunday, presumably because of snow cover and the fact the cold airmass over us is being very persistant.

Hopefully more such rins will appear on the 12z.

 

Edited by Quicksilver1989

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24 minutes ago, Nick L said:

I will be out getting merry for my birthday but I will try and get a sneaky peek :D But it's *just* coming into view on the 12z and it does look a bit further east on what I can see. 

What does this mean nick?

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1 hour ago, swebby said:

Good Q's and i also wonder why showers don't make it inland as far as i'd expect/hope.  The answers to your Q's will vary depending on what part of europe we look at but i'll have a pop at answering as an amateur but hopefully someone like John Holmes will give some expert answers.

If you look at the radar, it's actually currently very dry in France/Germany relative to  whats over the UK, the showers in northern Germany/Benelux may have resulted from an air mass that has travelled over the Baltic Sea plus i think the fax charts are showing a trough in the air flow for this location.  Italy/med coast is near some low pressure features and is arguably a battle ground scenario! The med sea temps will be higher than the N-Sea so if cold air engages with that then more precipitation. You will also need to consider the impact of mountain ranges like the Alps/Pyrenees/Transval Alps have on disrupting air flows.

Thanks Swebby. That’s really quite helpful. I’ve always wondered why. I have lots of friends in Germany and they always seem to get more shower activity in this flow. Given that places like Munich are not near the sea, I’ve always asked why doesn’t the U.K. get the same shower activity.

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